1. Field of the Invention
The present invention relates to the control of tools and the communication among tools in a multi-tool semiconductor processing environment. More specifically, embodiments of the present invention relate to a system, method and medium for control of and communication among wafer processing tools in a wafer processing environment.
2. Related Art
In today""s semiconductor manufacturing environment, a facility for the production of semiconductor products (such as, e.g., wafers) will typically contain multiple tools, each for performing one or more of a variety of functions. Thus, where a wafer is being processed into items such as logic (e.g., central processing units) or memory (e.g., DRAMs) units, each tool performs some specified function on the wafer, and then the wafer is passed on to the next tool. (The final product output, i.e., final state of the wafer, in this example, eventually gets cut up into individual chips, e.g., Central Processing Units, DRAM""s, etc.)
An example of a conventional semiconductor manufacturing facility is now described with regard to FIG. 1. Referring now to FIG. 1, a host computer 104 is shown as being in communication and control of the various aspects of the semiconductor manufacturing facility. More specifically, host computer 104 is in communication with Tools 1-3 (112-116, respectively) used to process (or inspect) semiconductor products. Thus, for example, Tool 1 (112) might be a deposition tool, while Tool 2 (114) might be a chemical mechanical polishing (CMP) tool.
For each tool shown in FIG. 1, there exists an associated station controller (106-110). These station controllers are used to facilitate the communication between the tools (112-116) and the host computer 104. Since the tools often have disparate protocols, it becomes necessary to implement the station controllers (106-110) to allow the tools to communicate using protocol common to the semiconductor processing facility, and thus communicate with the host computer 104. Such common protocols that may be used to ultimately communicate with the host computer 104 include SECS/GEM and HSMS.
In addition, host computer 104 is also in communication with a material transport control 102, which controls an external material transport system 118. The external material transport system 118 is what physically transports the semiconductor products (at their various stages of production) from one tool to another. (Typically, the semiconductor products are contained in cassettes, boxes or pods of 25 units.) Consequently, a semiconductor xe2x80x9ctoolxe2x80x9d can be defined as a device that performs a given function or functions on a given semiconductor product (e.g., a wafer), whereby some external material transport system is required to transport the semiconductor product to and from the tool (and, thus, from and to other tools).
Various deficiencies have been found to exist using the conventional semiconductor factory scheme as described above. These deficiencies typically relate to the problems associated with communication and control of the tools, and can have effects on both the quantity and quality of the final (and intermediate) semiconductor products. Some of these deficiencies are described below.
Conventional semiconductor processing facilities contain tools whose individual output (in terms of quantity and/or quality) is controllable, and can be set to some amount/specification for a given tool. However, each tool is just one part of the overall wafer production process. Furthermore, the output of a given tool typically results in at least some variation from wafer to wafer. Consequently, in order to accurately control the quality and quantity of the final output resulting from the work of multiple tools, it would be desirable to effectively coordinate the efforts of the multiple tools by, e.g., facilitating enhanced communication to and between tools. This would more readily facilitate, for example, 1) allowing a tool to send information forward to a second tool to compensate for the variations in the output (in terms of quantity and/or quality) of the previous tool, and/or 2) allowing a tool to notify a previous tool of a variation so that the previous tool can compensate by modifying its procedures for the benefit of subsequently-processed products. However, protocols (which are currently very host-centric) do not currently exist to readily facilitate communication among tools. Consequently, what is needed is a scheme to facilitate communication between two or more tools so that the final product output from a combination of tools can be more accurately controlled, adjusted and predicted.
Another problem with conventional semiconductor processing facilities relates to the modification of recipes for particular semiconductor products being processed in the semiconductor processing facility. (A xe2x80x9crecipexe2x80x9d is a sequence of steps that one or more semiconductor products are directed to go through within a given tool and/or series of tools.). Conventionally, if a recipe needs to be modified for a particular purpose (e.g., one or more individual semiconductor products needs to be specially treated), the entire recipe would become corrupt (e.g., the recipe would be changed and also there is no tracking or recording of the modifications made to the recipe for the individual semiconductor products. Consequently, what is needed is a scheme to systematically implement, track and record modifications made to an initial recipe for particular individual semiconductor products (e.g., such as semiconductor wafers) without corrupting the entire recipe.
Another deficiency with conventional schemes relates to determining whether a tool or set of tools, capable of producing a number of different products, and capable of implementing a number of different steps, is prepared to produce a particular semiconductor product that has been requested by the semiconductor processing facility (e.g., requested by the host computer 104), and/or is prepared to implement required/requested step(s). Here, examples of the different products are particular types of central processing units. Knowledge of such information is clearly important so that proper planning can be undertaken before materials are sent to the various appropriate tools in the semiconductor processing facility. Consequently, what is needed is a scheme for determining whether a tool or series of tools are ready for the production of a particular semiconductor product and/or for the implementation of required/requested steps. Knowledge of related information, such as when a tool or tools will be undergoing some type of maintenance (e.g., preventive maintenance), is also desirable to obtain in conjunction with whether one or more tools are ready for producing a given semiconductor product.
Yet another problem with conventional schemes relates to conveying historical (and related) information specifically regarding one or more semiconductor products to specific tools within the semiconductor processing facility as the semiconductor product(s) travel to those tools for processing or inspection. While conventional schemes can convey process or inspection information about semiconductor product(s) to the host computer 104 (for use in any number of disparate ways), these schemes do not actually and automatically associate information about the semiconductor product with the semiconductor product as it travels through the semiconductor processing facility or make this information available to process and inspection tools. Consequently, what is needed is a scheme for associating historical (and related) information with a semiconductor product as it travels (and is processed) through a semiconductor processing facility.
Because of the deficiencies mentioned above, tools need to be shut down for maintenance more frequently than might otherwise be the case. Specifically, when a semiconductor product is processed by a tool, the resultant semiconductor product typically contains at least some variance (e.g., in terms of crystalline structure and/or physical specification) from what is optimally desired. This variance can occur due to any number of factors, including 1) that parts of the tool are wearing down and/or, 2) that the tool is in a foundry environment, where it is requested to participate in the production of many different products over a relatively short amount of time (and the switching from one product to another does not, e.g., fully recalibrate certain aspects of the tool). At some point, if the variance becomes too great (despite efforts to, e.g., adjust the controls on the tool), the resultant semiconductor product will be unacceptable, and the tool causing the variance will need to be shut down for maintenance. However, if there were some way to convey variance information (e.g., historical and related information) to a subsequent tool, and the unacceptable variance can be compensated for by that subsequent tool, then the tool causing the variance could continue to operate without the need for a maintenance shut down. Allowing a tool causing the variance to operate for a longer period of time without requiring maintenance would clearly be beneficial from a cost and yield perspective.
The present invention alleviates the deficiencies of the prior schemes mentioned above by providing a system, method and medium for facilitating communication among tools in a semiconductor (e.g., wafer) processing facility. In particular, the present invention provides greater control of the overall semiconductor product output of groups of tools in terms of the quantity and/or quality of a final semiconductor product. Embodiments of the present invention contemplate that this is implemented by providing enhanced communication among a group of tools which form a xe2x80x9cmodulexe2x80x9d (where the module is contemplated to provide some designated function or functions). This communication can be facilitated via a module control mechanism, which could be a separate xe2x80x9cmodule controller,xe2x80x9d and/or computer/communications facilities residing in the individual tools themselves. This enhanced communication allows for more effective feedback and feed forward capabilities so that variations found in a particular semiconductor product can effectively and automatically trigger appropriate compensation mechanisms.
More specifically, the present invention contemplates implementing the above-mentioned concepts by providing that modifications to a recipe can be made to one or more semiconductor products without it affecting (e.g., corrupting) the entire recipe. Also, such special modifications are recorded, so that they can be noted by subsequent (or previous) tools. As part of (or possibly separately from) this, the present invention also contemplates that a xe2x80x9ctraveling informationxe2x80x9d file can be associated with one or more wafers, and travel with the one or more wafers throughout the semiconductor processing facility.
In addition, the present invention also provides facilities to query one or more tools to determine whether or not the tools are ready for the production of a specified semiconductor product (and when in the tool""s maintenance cycle some type of maintenance is scheduled to occur) and/or for the implementation of required/requested steps so that appropriate actions can be taken.